1. Field of the Invention
The invention generally relates to the direction of combustion air into a furnace and, more particularly, to a new and novel louvered after-air port which allows the flow direction to be concurrently adjusted both horizontally and vertically.
2. Description of the Related Art
Removing a portion of secondary air from pulverized coal fired burners effectively reduces nitrous oxide emissions from combustion processes in utility and industrial burners. The removed portion of the secondary air is diverted to ports which introduce it later in the combustion process. In many applications, the ports are located above the burner zone in furnaces arranged for gases to travel upward and out. Such ports are sometimes referred to as overfire air ports. In other applications, the ports are placed beneath or with the burner zone and are referred to as under-fire air ports. The overfire and under-fire air ports may also be referred to as after-air ports.
The ports are provided with a single set of louvers that allow the air to enter the boiler at an angle to entrain the gases and optimize the air flow to reducing, oxygen-starved locations.
Known louvered ports, which utilize a single set of louvered vanes, have adjustable vanes that permit adjustments to improve the performance. These louvered ports, however, do not allow adjustments to move the air both horizontally and vertically, or in a combination of the horizontal and vertical directions. As a result, the port cannot always be oriented to provide the best results.